Documentation

Background

Civic Electromagnetic Cymatics (CEMC) is a project developed by Josh Fisher, Anna Weisling and Sandjar Kozubaev as part of their graduate studies in digital media at Georgia Institute of Technology. The project uses the practices of hacking and citizen science to explore electromagnetic radiation emitted by everyday objects.

DIY Electromagnetic Field Detection

Electromagnetic field  (EM or EMF) is a physical field produced by objects which are charged with electricity. It is one of the fundamental forces of nature but it is very strong and detectable in objects that use electricity. However, as much as we are surrounded by such objects we do not hear or see their EMF fields. The focus of this project is not the effects of EMF field on the human body, but on ways by which we can detect and perceive EMF.

There are many ways to detect EMF, including commercial devices. In this project, we decided to hack an old portable cassette player. Our idea was inspired by this YouTube video . We also found instructions to make an EMF detector using an Arduino board here. The advantage of using a cassette player is that the EMF is converted into sound offering various creative possibilities.

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Figure 1: The “Walkman” Cassette Players: The magnetic head of the player is very sensitive. To counter the sensitivity, the magnetic head is usually grounded to the chassis. Disconnecting the grounding screws makes the head more sensitive to EMFs.

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Figure 2: Hacking “Walkman”

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Figure 3: The Magnetic Head

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Figure 4: The Magnetic Head Ungrounded

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Figure 5: 3.5 mm Splitter

 

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Figure 6: Hunting for EMF

We disassembled the housing of the player, disconnected the grounding and reassembled it. There is another advantage of using an old cassette player which is the housing unit itself. The housing makes it easier to conduct field work and record sounds in hard to reach places.

 

Recording Sounds in the Field

 

To record the EM sounds we connected the cassette player to a digital voice recorder. We used a splitter to connect both the digital recorder and headphones to the cassette player. This is crucial because EMF is strongest in specific places and the device needs to be held precisely and steadily to record consistent sound. We found it more productive to conduct field work with two people, with one focusing on recording of sounds and one capturing video and photo documentation. We surveyed various locations on Georgia Tech campus, including parking lots, surroundings of residential buildings, a power plant and office spaces.

 

Sonification

 

The sonification process for this project involved three main steps: capturing, filtering, and transduction. The sound of the electromagnetic signals produced by buildings and objects directly from 3.5mm audio output on the cassette player. We analyzed and edited the sounds down to their most unique and consistent sections, for easier distinction between final sound palates. Next, we analyzed and filtered them in the audio manipulation program Audacity in order to reduce extraneous noise that was introduced into the signal chain by auto-mechanical and unrelated external sound sources. The selected audio clips each had strong fundamental frequencies (the frequency which is perceived, usually, as the “loudest” or most distinct to the human ear), and similar noise profiles, which were attenuated as equally as possible. This process of equalization generally involved high- and low-pass filters, as well as more specifically targeted attenuation at “problem” frequencies, if needed. The pre- and post-equalized spectral plots of a single audio file, as well as the equalization settings used, can be seen in Figures 8-10.

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Figure 7: Hunting for EMF

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We then exported the equalized audio and manipulated it in the programming software Max/MSP. Initial concepts involved the detection of each sound file’s fundamental frequency and subsequently reproducing that frequency using a sine wave generator, which provided a pure tonal output free of additional harmonics and/or noise. This process can be seen in figure 1.

 

Although the system programmed in Max/MSP handled the frequency detection and reproduction processes as expected, the continual, minute pitch shifts in the recordings prevented the output of a strong, unwavering note. Because the presence of a strong fundamental pitch was not the issue, but rather the small variations over time, we constructed the second iteration of the Max/MSP to “freeze” the recordings in time, outputting the frequency content of a singular moment. This was possible through a process called “fast fourier transform” (FFT), wherein an extremely detailed snapshot of the frequencies at any given point of the audio file can be recorded and reproduced, effectively stretching the single audio instant ad infinitum. This process can be seen in figure 12.

 

This sound, taken from the cleaned recordings and reproduced in Max, was used to visualize the EM frequencies in the non-Newtonian liquid, which was situated in a plastic dish directly on the cone of a subwoofer. Initially a specialized “bass puck” (figure 13) was used for this purpose, with the assumption that an emphasis on powerful bass frequencies and ability to mount directly to vibration materials would produce satisfactory results. For unknown reasons, the effectiveness of this transducer was disappointing, and when compared to a simple subwoofer cone (removed from its housing, Figure 14) it became clear that a generic subwoofer was a more effective option.

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We tested several vibratory surfaces including sheet metal, wood, plastic, and acrylic (Figures 15-16), and experiments with the cymatic material were also done with rice, plastic pellets, sand, and water (Figures 10-11). Though these materials all offered different results, to varying levels of appeal, the final materials chosen were non-Newtonian fluid and plastic. We made non-Newtonian fluid using corn starch and water (2:1 ratio)

 

By sending this sonic energy through the speaker, the plastic dish vibrated at varying pitches attuned with its own resonant frequency (we found that multiples of 50 Hertz were particularly successful). The plastic membrane, physically vibrating at its natural energy, transferred the patterned movements to the non-Newtonian liquid it held, which in turn revealed the patterns for photographic capture.

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Figure 15: 

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Video

In preparation for the final filming of the project, aesthetic considerations were taken into account. The plastic dish was mounted directly onto the speaker cone with four screws, and a simple wooden housing was created, designed to the precise measurements of the speaker and plastic dish, and laser cut out of acrylic (figure 19). Each audio file was filmed from above, with careful attention to identical framing in order to highlight unique differences between cymatic patterns.

The first round of filming involved unmodified cymatic fluid, while a second round experimented with food coloring introduced into the material (Figures 20-21). Upon reviewing the footage, we decided to use the un-dyed videos in order to present patterns on equal footing (as filming went on, the dye mixed more and more, eventually coloring the fluid unevenly).

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figure_20 Figure 20: figure_21 Figure 21: figure_22 Figure 22: figure_23 Figure 23: 
 

We imported the footage into editing software Final Cut Pro X, and trimmed to appropriate lengths. The final aesthetic decision of this project involved two visual effects/filters: one mask to cover the materials and environment surrounding the plastic dish and housing, and one effect to emphasize the patterns which were revealed in the liquid. The resulting footage presents the cymatic patterns clearly and invokes a physical representation of the electromagnetic fields that each of us experiences every day—a force that exists somewhere between the micro and macro worlds, amongst biological, terrestrial, and cosmic bodies (Figures 22-23).

 

Key Insights

 
During this project, we uncovered several insights about electromagnetism in devices and about visualization. Sensitivity of the EMF is key to recording a consistent sounds. One has to be in close proximity to the object, more specifically close to the greatest concentration of electricity. For the person who records the sounds, this created a novel interaction with the objects. To find the most optimal spot to detect EMF, one hast to probe it in various places which are sometimes hard to reach.  Probing objects this way creates a new awareness of the object “from the inside” and sets new expectations about where the “best spot” might be. Furthermore, visualizing sound with cymatics creates a more direct and physical relationship between the sound and the perceivable world. As we calibrated the visualization device and experimented with various quantities of fluid, it became clearer what creates more dynamic and consistent visualizations.
 

Future Considerations

 
In the future, we would like to test live cymatics of EM sounds with an audience and record their reactions.  In addition, we would like to record more sounds from other devices and catalogue them to promote greater awareness about